The three representatives in this taxon were designated as the outgroup for one analysis based on previous indications of their sister-group relationship with the Anomura (Martin & Abele, 1986; Poore, 1994). The outgroup was unable to be retained as a monophyletic clade as both Thalassina and Trypaea shifted to the ingroup, allying themselves with Hippa and Panulirus, respectively (these latter associations were maintained in the analysis shown in Fig. 1 & Fig. 2). In all analyses, the Thalassinoidea were never retained as a monophyletic group. Paraphyly of these thalassinoids reflects the very diverse spermatozoal morphologies exhibited by the three representatives (Tudge, 1995a, b), each from a separate superfamily (Poore, 1994). Monophyly of the Thalassinidea has been proposed by Poore (1994) and Scholtz & Richter (1995)but has previously been disputed by Gurney (1942) and de Saint Laurent (1973). This latter view of paraphyly of the Thalassinidea would here appear to receive support from spermatozoal ultrastructure.